Transesterification tallow

In a previous patent, Bayense et al. reported the use of ETS-10 and ETS-4 for the transesterification of TGs with alcohols.In their studies, both batch and fixed bed reactors were used to conduct the reaction. Under batch conditions, reactions were carried out at 220°C, 21 bar, and a catalyst loading of 0.23 wt% based on total autoclave content. Experiments with soybean oil and methanol, at a methanol/oil ratio of 4.2, resulted in 69.0% total oil conversion with an ester yield of 52.6% for ETS-10 and 96.9% conversion with an ester yield of 85.7% for ETS-4. When tallow was used under the same conditions, conversion and ester yield were 30.6% and 19.1% for ETS-10 and 44.1% and 29.6% for ETS-4, respectively. The slightly better activity shown by ETS-4 might imply that only basic sites at the pore opening of these zeolites were catalyzing the reaction. The effective radius of the TG molecule is such that it can not enter through the small pore openings of ETS-4 (diameter of 3.7 A) or even ETS-10... 

Parrish (1977) reviewed the research and development of lactose ester-type surfactants carried out by Scholnick and his colleagues (Scholnick et al. 1974, 1975 Scholnick and Linfield 1977). Their initial attempts to form lactose esters followed the same transesterification procedures that had been used with sucrose (a fatty acid methyl ester in N,N-dimethylformamide with potassium carbonate as the catalyst). Their successful approach was the reaction of lactose in N-methyl-2-pyrrolidone as the solvent with fatty acid chlorides, resulting in yields of 88 to 95% for esters of lauric, myristic, palmitic, stearic, oleic, and tallow fatty acids. The principal product was the monoester, which is important for detergent use, since diesters and higher esters of lactose are not water soluble. 

With the same system applied to the transesterification of tallow, and an excess of 10 moles of glycerol per mole of triglyceride, a conversion of 38.8 % (weight) in monoglycerides was observed, the rest being diglycerides from the initial substrate,... 

To obtain substantial yields of surfactant hydrophobes, especially in the most useful C12— 14 range, the choice is restricted to coconut, palm and palm kernel oils. In the C16-18 range, the same oils are also used but animal (normally beef) tallow can be used. The use of animal fats raises some ethical issues but these are not commonly used to produce anionic surfactants. The oils may be converted to methyl esters by transesterification which allows easier distillation to remove heavy/light fractions and the esters are finally hydrogenated to fatty alcohols. Alternatively, the fat or oil can be hydrolysed to fatty acid prior to esterification... 

First we wanted to avoid the formation of a middle chain monocarboxylic acid (pelargonic acid) as a by-product. Second oleic acid or its methylester are, not industrially available in pure form. Produced by hydrolysis or transesterification of tallow or vegetable oil, they are always contaminated by other C18-fatty acids/methylesters, as for example linoleic acid/methylester, which cannot be separated in an economic manner. 

Ma, F. L.D. Clements M.A. Hanna, biodiesel fuel from animal fat. ancillary studies on transesterification of beef tallow. Ind. Eng. Chem. Res. 1998a, 37, 3768-3771. 

The process originally selected involved transesterification between a triglyceride (fat, e.g., tallow) and sucrose in dimethylformamide (DMF-a mutual solvent) in the presence of a catalyst (potassium carbonate -K2CO3) at a temperature of 90°C. Under these conditions the fatty acid underwent transfer to sucrose giving a complex mixture of mono- and diglycerides and sucrose esters. The reaction is not complete and the product also contains unreacted sucrose and tallow, giving problems in purification and analysis. 

Chung, K.-H., J. Kim, and K.-Y. Lee. 2009. Biodiesel Production by Transesterification of Duck Tallow with Methanol on Alkali Catalysts. Biomass and Bioenergy 33... 

Ma, R, L. D. Clements, and M. A. Hanna. 1998. Biodiesel Fuel from Animal Fat. Ancillary Studies on Transesterification of Beef Tallow. Industrial and Engineering Chemistry... 

Table I shows the multi output process of the biodiesel from tallow model. Four processes have more than one economic output. For the life cycle of biodiesel from used vegetable oil only the two letter processes (transesterification and KOH-production) are relevant.

Kwon, E.E., et al, 2014. Transforming duck tallow into biodiesel via noncatalytic transesterification. Applied Energy 116, 20—25. Available at http //www.sciencedirect.com/ science/article/pii/S0306261913009495 (accessed 01.03.15.). 

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